Vegetation changes at sub-xeric urban forest edgesin Finland – the effects of edge aspect and trampling

Leena Hamberg & Katja Fedrowitz &

Susanna Lehvävirta & D. Johan Kotze

Published online: 14 August 2010# Springer Science+Business Media, LLC 2010

Abstract The relative strengths of the effects of forest edges and recreational use onunderstorey vegetation were studied at sub-xeric boreal urban forest edges in the greaterHelsinki region, Finland. The study was performed at northern, eastern, southern andwestern edges, and vegetation sample plots were placed on, next to and away from pathswith different trampling intensities 0–107 m from the forest edges. We found that humantrampling altered vegetation more than the effects of forest edges. Vegetation changeddramatically on paths and the effects of path edges were seen in seemingly untrampledvegetation at least up to 4 m from the path edge. However, our results suggested that theeffect of the edge may penetrate up to 50 m into forest interiors. Changes in vegetationcomposition indicated that the effects of the edge were stronger at eastern, southern andwestern than at northern edges.

Keywords Fragmentation . Understorey vegetation . Species composition .

Urban woodlands

Urban Ecosyst (2010) 13:583–603DOI 10.1007/s11252-010-0142-7

L. Hamberg (*)Finnish Forest Research Institute, P.O. Box 18, FI-01301 Vantaa, Finlande-mail: leena.hamberg@metla.fi

K. FedrowitzDepartment of Ecology, Swedish University of Agricultural Sciences (SLU), P.O. 7044,SE-75007 Uppsala, Swedene-mail: katja.fedrowitz@ekol.slu.se

S. LehvävirtaBotanic Garden, Finnish Museum of Natural History, University of Helsinki,P.O. Box 44, FI-00014 Helsinki, Finlande-mail: susanna.lehvavirta@helsinki.fi

D. J. KotzeDepartment of Environmental Sciences, University of Helsinki, P.O. Box 65, FI-00014 Helsinki, Finlande-mail: johan.kotze@helsinki.fi

Introduction

Small fragment size, edge effects and the intensive recreational use of forests are likelycausal factors for the decrease of native vegetation in urban environments (Ewers andDidham 2006; Godefroid and Koedam 2003; Malmivaara et al. 2002; Malmivaara-Lämsä etal. 2008a). Here, we investigated the effects of forest edges, edge aspect and trampling onforest understorey vegetation in the greater Helsinki area, Finland, where forests withnatural forest vegetation still exist.

Forest fragmentation increases the proportion of edge habitat, which is more exposed towind, solar radiation and urban load than interior forest habitat (e.g. Bannerman 1998;Chen et al. 1995; Weathers et al. 2001). Edges are, consequently, windier, warmer, drier andmore nutrient-rich than forest interiors (see Didham and Lawton 1999; Malmivaara-Lämsäet al. 2008b). In the northern hemisphere, effects of the edge (in terms of light, air and soiltemperature, relative humidity and soil moisture) are especially strong at south to west-facing edges and weaker at northern and eastern edges (Chen et al. 1995; Gehlhausen et al.2000). Thus, at south to west-facing edges forest communities may be considerablydifferent from forest interiors (Hamberg et al. 2008), while communities at other edges maybe less affected by the edge.

Apart from the potential negative effects of edges on original forest vegetation in smallurban forests, recreational use of these forests usually increases with increasing numbers ofresidents in the vicinity, decreasing the cover of understorey vegetation (Lehvävirta 1999;Malmivaara et al. 2002; Malmivaara-Lämsä et al. 2008a). When vegetation coverdiminishes due to trampling, conditions may become warmer, drier and more nutrient richon paths (see Liddle 1997; Malmivaara-Lämsä et al. 2008b) creating small scale edgeeffects on vegetation off the paths (Hamberg et al. 2008).

The aim of this study was to determine the relative effects of forest edges and (human)trampling in shaping the vegetation of boreal sub-xeric Vaccinium type urban forests in thegreater Helsinki region, Finland. The effects of habitat edges and trampling on vegetationcommunities have been studied widely (e.g. Harper et al. 2005; Liddle 1997; Malmivaara etal. 2002; Murcia 1995) but few authors have attempted to study these factors together toreveal their relative importance in shaping urban forest vegetation. Studies on the combinedeffects of habitat edges and trampling in urban forest patches are important not only ingaining insights into ecological patterns but also in providing recommendations on how topreserve sensitive species. A previous study in mesic, medium fertile Myrtillus forest sitetype in Helsinki suggested that both the edge effect and trampling are strong determinantsof forest understorey vegetation, and that the edge effect extends up to 50 m into forestinteriors (Hamberg et al. 2008). Here we examine if the same applies to less nutrient-rich,sub-xeric urban forests. Because only south to west facing edges were studied in mesicurban forests (Hamberg et al. 2008), all edge aspects were included in the present sub-xericforest type study to enhance our knowledge on the possible role of aspect in shapingunderstorey vegetation.

We hypothesized that both the effects of the edge and of trampling are changingunderstorey vegetation in urban sub-xeric forests. We assumed further that 1) the effects ofthe edge are more pronounced and penetrate deeper into forests at southern and westernedges than at northern and eastern edges in these northern hemisphere forests (cf. Chen etal. 1995; Gehlhausen et al. 2000). Thus, we expected that plant species known to be edgesensitive would be low in cover and those known to be edge favouring to be high in coverfurther into the forest at southern and western edges as compared to northern and easternedges. We also expected understorey vegetation composition to be most affected at southern

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and western edges. 2) We assumed most plant species to suffer from the effects of tramplingon paths, and to change in cover next to and away from paths due to smaller scalemicroclimatic changes on paths. Species a priori classified as trampling sensitive wereexpected to be higher in cover away from the paths, while for more tolerant species wehypothesized that they may be higher in cover right next to a path than further away. It wasassumed that trampling intensity of paths will affect the covers and probabilities ofoccurrences of plant species off the paths.

Materials and methods

Study area and site selection

The undestorey vegetation of sub-xeric Vaccinium vitis-idaea forest site type or Vacciniumtype mixed with medium fertile Myrtillus type (Cajander 1926) was examined in themetropolitan area of Helsinki (including the cities of Helsinki, Espoo and Vantaa) andTuusula, southern Finland (66° 84′N, 33° 87′E). The study area is situated in the hemiboreal—southern boreal vegetation zone (Ahti et al. 1968). The vegetation of Vaccinium forest type isrelatively xerophilous and is found on rather dry and sandy soils, glacial ridges, and onmoraines throughout Finland. The understorey vegetation in Vaccinium type forests ischaracterized by an abundance of bryophytes and dwarf-shrubs including V. vitis-idaea, V.myrtillus and Calluna vulgaris, and lichens that can be found especially at the base of treesand in relief surfaces (Cajander 1926; Kuusipalo 1996). Grasses and herbs occur sparsely.Scots pine (Pinus sylvestris) is the general forest forming tree species.

Mature trees of the studied forest patches were at least 80 years old and the forests hadneither been affected by natural disturbances, such as storms, nor had they been managedduring the last 10 years. None of the patches were on slopes. Urban forest patch edges weredefined as the outermost line of mature trees and the edges were at least 10 years old. Allstudied edges faced artificial surfaces such as roads, residential or industrial areas, but edgesfacing motorways with heavy traffic loads were avoided.

Sampling

Altogether 256 vegetation plots (plot size 0.5 m2) were sampled from the 22nd of June tothe 20th of July 2005 at 19 urban forest edges. We were able to find 30, 74, 79 and 73sample plots suitable for the study at northern (316–45°), eastern (46–135°), southern(136–225°) and western (226–315°) edges, respectively. Sample plots were placed 0–107 m from the forest edges into the interiors on, next to (at 0.45 m) and further away (atleast 2 m) from paths of different trampling intensities. To ensure an adequate number ofobservations of each forest edge distance and trampling intensity combination, replicateswere collected at four edge distance categories (0–15 m, 15.1–30 m, 30.1–60 m and>60 m) and four trampling intensity classes (1–4, see below). Where possible,randomization was used to choose distance from the forest edge, distance from the pathedge and the side of a path where sample plots next to and away from a path was placed.However, sample plots at northern edges were situated only between 0 and 18 m from theedges as we were unable to find large enough forest patches of this site type with northernedges. Sample plots were not placed if the edge from another aspect was closer than thestudied edge. Trampling intensities were classified based on the amount of wear on thepaths (Lehvävirta 1999): wear class 1 = visible effects of wear, vegetation damaged, but

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only slightly reduced in cover; wear class 2 = visible effects of wear, vegetation damaged andreduced in cover, but not completely worn away; wear class 3 = generally no vegetation on path,humus layer not worn away, rocks and tree roots sometimes uncovered; wear class 4 = baremineral soil or a deeply worn humus layer, no vegetation remaining, and rocks and tree rootsoften uncovered. For each plot, distance from the forest edge and distance from the path edgewere measured, and wear class of the paths estimated (Table 1). Distance measurements werealways taken from the forest and path edges to the centre point of the sample plot. Distancesfor the sample plots on the paths were negative in order to make a distinction between plotson the paths and those off the paths.

The vegetation was studied based on visual percentage estimation of plant covers ofeach species within the sample plots (scale: 0, 0.1, 0.2, 0.5, 1, 2, 3,..., 99, 100%). Plantsinventoried included vascular plants with tree and shrub saplings <30 cm in height,bryophytes and lichens, and were identified using the nomenclature of Hämet-Ahti et al.(1998) for vascular plants, Koponen (1994) for mosses, and Ahti (1989) for lichens. Inaddition, tree diameters were measured at breast height (dbh, at 1.30 m above ground level)in a 50 m2 circle around each vegetation sample plot for trees with a dbh of ≥5 cm. Thisinformation was used to calculate the volumes of trees per hectare (the formulas ofLaasasenaho in Hyvämäki 2002) (Table 1).

Data analyses

The effects of the edge and trampling on the composition of understorey vegetation wereinvestigated using global non-metric multidimensional scaling (GNMDS). First, 250vegetation sample plots on, next to and away from the paths, from forest edges to theinteriors were included in the analysis to determine which of these variables, i.e., forestedge or trampling, had a greater effect on understorey vegetation composition. Six of the256 sample plots had no plant species and were not included in the analysis. Second, onlysample plots away from the paths (≥2 m from path edge) were used to analyze the edge

Table 1 Means and SE of variables measured from the 256 urban sub-xeric forest vegetation plots selected.Minimum and maximum values for distance from the forest and path edges are shown in parentheses.Negative values of distances from path edges mean distances from path edges to the centre point of the paths.Other broad-leaved trees include Populus tremula, Sorbus aucuparia and Salix caprea

NORTHmean ± SE

EASTmean ± SE

SOUTHmean ± SE

WESTmean ± SE

Variable n=30 n=74 n=79 n=73

Distance from the forest edge (m) 8.8±1.2(0–18 m)

35.8±3.3(0–107 m)

37.0±3.2(0–92 m)

41.8±2.9(2–81 m)

Distance from the path edge (m) 1.0±0.3(−1–4 m)

1.0±0.2(−1–9 m)

0.9±0.2(−2–8 m)

1.1±0.2(−1–11 m)

Volume of Pinus sylvestris (m3ha−1) 144.2±21.5 124.3±13.7 185.7±13.2 145.0±9.7

Volume of Picea abies (m3ha−1) 17.4±7.5 22.9±5.4 14.0±4.1 9.2±4.3

Volume of Betula pendula andB. pubescens (m3ha−1)

9.9±5.5 21.7±7.1 1.9±0.9 14.3±5.3

Volume of other broad-leaved trees (m3ha−1) 2.9±1.8 6.6±2.5 0.6±0.3 0.9±0.8

Total volume of broad-leaved trees (m3ha−1) 12.9±5.6 28.3±8.7 2.5±0.9 15.2±5.4

Total volume of conifer trees (m3ha−1) 161.6±20.7 147.1±13.0 199.7±12.6 153.1±9.8

Total volume of trees (m3ha−1) 174.5±21.9 175.4±14.0 202.2±12.5 168.3±10.7

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effect and the effects of edge aspect (n=82). Sample plots on and next to the paths were notincluded in the second GNMDS because we needed to minimize the effects of trampling inorder to focus on the edge effect. The three-dimensional solutions performed best, in termsof minimising the stress values and maximising the correlations of environmental variablesand variables describing vegetation composition with the vegetation data. For the edgeeffect GNMDS (i.e., plots ≥2 m from the path edge included), the log-transformed solutionwas selected. The Bray-Curtis coefficient was used as a dissimilarity measure, andpermutation tests were applied in the vector fitting procedure (Oksanen 2004). Theordination figures included environmental variables and variables describing vegetationcomposition that had a correlation of >0.30 and were statistically significant (p≤0.05).

Based on prior knowledge (e.g. Hamberg et al. 2008; Hämet-Ahti et al. 1998; Ingelög etal. 1977; Malmivaara et al. 2002; Reinikainen et al. 2000), species were classifiedaccording to their tolerance or sensitivity to edge and trampling effects (Appendix A).Species with similar predicted responses were grouped if they occurred in less than 30% ofthe sample plots. All species and species groups that occurred in at least 30% of the plotswere analyzed individually (Table 2).

To test our hypotheses, generalised linear mixed models (GLMM) were performed (RDevelopment Core Team 2005; Venables and Ripley 2002). Sample plots from the northernaspect were excluded from these analyses because of low numbers of plots, and becausethese plots extended only 18 m from the forest edges into the interiors (see Table 1). Coverpercentages and occurrences (frequencies) of five species and of four species groups wereused as response variables in the analyses (Table 2). The GLMMs included one randomfactor (forest site), and eight fixed effect variables (tree volume (m3ha−1), proportion ofconifer trees (%), distance from the path (in m), wear class (1–4, specified as an orderedfactor), aspect, linear edge distance term (in m, x-average(x)), squared edge distance term(x-average(x))2, and cubic edge distance term (x-average(x))3). Squared and cubic terms

Table 2 Predicted responses of the plant species and species groups to edge and trampling effects in sub-xeric urban forests. Only species and species groups occurring in at least 30% of the sample plots wereincluded in the models

TRAMPLING

Very low tolerance Low tolerance Moderate to high tolerance

EDGE Sensitive Vaccinium myrtillus Dicranum scoparium

Vaccinium vitis-idaea

Pleurozium schreberi

Dicranum polysetum

Favouring Edge favouring speciesa Melampyrum speciesb Tolerant speciesd

Grass speciesc

a The Edge favouring species group includes Brachythecium species (36), Cladina rangiferina (3), Pinussylvestris (38) and Solidago virgaurea (2). Frequencies of species are in parentheses, for exampleBrachythecium species occurred in 36 of the 256 plots sampledbMelampyrum species includes M. pratense (53), M. sylvaticum (12) and undefined Melampyrum spp. (5)c The Grass species group includes Calamagrostis arundinacea (11), C. epigejos (6), Deschampsia flexuosa(59) and Luzula pilosa (23)d The Tolerant species group includes Agrostis capillaris (1), Ceratodon purpureus (2), Cetraria islandica(8), Convallaria majalis (17), Festuca ovina (4), Poa spp. (8), Pohlia nutans (35), Polytrichum juniperinum(3), Rhytidiadelphus squarrosus (3) and Rumex spp. (2)

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were included to allow for a curvilinear response of the species to distance from the edge.Because we wanted to investigate the effects of edge aspect on the spatial extent of the edgeeffect, we included an interaction term into the models between aspect and the edge terms(linear, squared and cubic edge distances). The response variables were modelled followingquasi-binomial error distributions for cover percentages and as binomial error distributionsfor occurrence models. Tree volume and the proportion of conifer trees were used in themodels as these had previously been reported to have an effect on the understoreyvegetation (e.g. Hamberg et al. 2008; Malmivaara-Lämsä et al. 2008a). However, nopredictions were made as to how these variables would influence the vegetation as theywere primarily included to reduce the amount of variation in the models. A stepwiseprocedure was used to optimize the models for each species or species group, usingAkaike’s Information Criterion (AIC) and p-values as decision criteria (see Hamberg et al.2008). In addition, GLMMs were performed on the same response variables without the on-path data as we expected on-path data (i.e. sparse vegetation) to have an unduly influenceon response curves drawn for data next to and away from the paths.

Results

Trampling appeared to be a stronger factor than edge effects in shaping forest understoreyvegetation in sub-xeric urban forests (see Table 3, Fig. 1a in which distance from the forestedge was not an important factor compared to distance from the path). However, proximityof the forest edge affected the covers and probabilities of occurrences of some species(Appendix B, Fig. 2), and changes in the composition of the understorey vegetation suggestthat the spatial extent of the edge effect in these sub-xeric urban forests may be tens ofmetres (Table 4, Fig. 3a). Yet, contrary to expectations, edge effects were not mostpronounced at southern and western edges, and no clear pattern in terms of edge aspectcould not be observed (Appendix B, Fig. 2). Only slight differences between northern andother aspects were detected (Fig. 3b).

Trampling effects were strong on the paths, but the effects on vegetation were also foundnext to the paths, in the seemingly untrampled vegetation (Appendix B, Table 5, Fig. 4).Many forest species typical of sub-xeric vegetation suffered from the effects of tramplingwhereas some trampling-tolerant species low in cover in untrampled vegetation increased incover, especially on paths of intermediate trampling intensity.

Table 3 Maximum correlations (r) of vectors in the three-dimensional GNMDS solution (see Fig. 1) andtheir statistical significance (p). Sample plots including plant species on, next to and away from the paths atsub-xeric northern, eastern, southern and western forest edges were analyzed (n=250)

Variable r p

Wear class (1–4) 0.35 <0.001

Distance from the path (m) 0.50 <0.001

Total cover (%) 0.85 <0.001

Ground layer cover (%) 0.65 <0.001

Field layer cover (%) 0.68 <0.001

Dwarf shrubs cover (%) 0.67 <0.001

Number of species 0.32 <0.001

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Effects of the edge

According to changes in the understorey vegetation, edge effects seemed to disappearwithin the first 50 m from the forest edge, as sample plots more than 50 m from the forestedge clustered close to each other in the GNMDS (Table 4, Fig. 3a; see the direction of theedge vector). Thus, vegetation in all plots further than 50 m from the forest edge are ofsimilar vegetation, i.e. changes due to edge effects could not be detected at the understoreyvegetation level, even though the spatial extent of the edge differed for individual species(Appendix B, see Fig. 2). Species known to be edge sensitive decreased in cover close tothe edge, while species favouring edges had highest cover close to the edge. One exception

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Fig. 1 a Three-dimensionalGNMDS ordination of vegetationsample plots on, next to andaway from the paths, from sub-xeric urban forest edges to theinteriors at northern, eastern,southern and western edges(n=250). Dimensions 1 and 2are presented. The length of eachvector indicates the correlationbetween the vector and theunderstorey vegetation (seeTable 3). Field layer cover = allvascular plants; ground layer =bryophytes and lichens; totalcover = summed cover ofall understorey species; wearclass = the level of wear of paths(wear classes 1–4). b Speciesordination of the same sampleplots. Species occurring in atleast four sample plots arepresented. Species abbreviationsare presented in Appendix A

Urban Ecosyst (2010) 13:583–603 589

was the moss species Dicranum scoparium that was classified as an edge sensitive species,but responded as an edge favouring species.

Ground layer cover (mainly mosses) increased with increasing distance from the forestedge (Fig. 3). Most typical moss species of sub-xeric vegetation, such as Dicranumpolysetum, Pleurozium schreberi and Hylocomium splendens, occurred in the forestinteriors. Grasses, especially Deschampsia flexuosa, and broad-leaved trees were abundantnear the edges. The field layer, dwarf shrub and herb covers, and the number of specieswere higher near the edges than in the forest interiors. Although the covers of plant speciesgroups changed due to the effects of the edge, and the number of species increased near theedge line, clear changes in species due to the effects of the edge or the invasion of culturalspecies or species not belonging to the natural forest understorey vegetation of this foresttype were not observed (Fig. 3c).

VACCINIUM MYRTILLUS

0 20 40 60 80

PLEUROZIUM SCHREBERI

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DICRANUM POLYSETUM

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Fig. 2 Species and species group responses to eastern (—), southern (- - -) and western (∙∙∙) edges, 0–80 mfrom sub-xeric urban forest edges. Upper parts of the figures show cover responses and lower parts thespecies probabilities of occurrences. Curves are drawn using predicted values of the GLMMs (see Table 2and Appendix B)

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We hypothesized that the effects of the edge would be more pronounced at southern andwestern edges than at northern and eastern edges. Contrary to our expectations, cleardifferences between edge aspects were not found (Appendix B and Fig. 2). In addition, e.g.the cover and the probability of occurrence of the edge favouring grass species group werehigh at eastern edges and low at western edges. However, almost all northern edge sampleplots (0–18 m from the forest edges) grouped with plots further than 50 m from the forestedge indicating that the edge effect may not be pronounced at northern edges (Fig. 3a–b).

An increase in tree volume around the sample plot was associated with a decrease in thecover and probability of occurrence of Vaccinium myrtillus, whereas an increasedproportion of broad-leaved trees was associated with a decrease in the cover of D.polysetum and an increase in the cover of Vaccinium vitis-idaea and the cover and theprobability of occurrence of the edge favouring species group (Appendix B).

Effects of trampling

Sub-xeric vegetation was clearly altered by trampling on paths, but the effects of paths werealso observed in the seemingly untrampled vegetation off the paths (Appendix B, Table 5,Fig. 4). The cover of the dwarf shrub Vaccinium vitis-idaea, one of the most abundantspecies sampled, increased with increasing distance from the path edge. This effect wasobserved at least 4 m from path edges. Almost all species or species group covers orprobabilities of occurrences off the paths were affected by trampling intensity on the paths.The probability of occurrence of Vaccinium myrtillus and the covers of Pleuroziumschreberi and Melampyrum species were lower, and the covers of grass species and theprobability of occurrence of Dicranum scoparium were higher off the paths when tramplingintensity increased on the path. The edge favouring species group was more tolerant totrampling than expected (Tables 2 and 5, Fig. 4).

In terms of vegetation composition, sample plots on paths differed clearly from plots offthe paths (Table 3, Fig. 1a). Furthermore, the number of species decreased with increasingtrampling intensity. The effects of paths were seen in untrampled vegetation even whensample plots on and next to the paths were excluded from the analysis (Fig. 3a–b, Table 4).The further a plot is from the path edge the more the vegetation resembles unchangednatural vegetation in the forest interior. D. scoparium, Pohlia nutans and Cladonia spp.occurred frequently on the paths, but many species of sub-xeric forests, such as V. vitis-

Table 4 Maximum correlations (r) of vectors in the three-dimensional GNMDS solution (log transformed,see Fig. 3) and their statistical significance (p). Sample plots away from the paths at northern, eastern,southern and western sub-xeric urban forest edges were included in the analysis (n=82)

Variable r p

Volume of broad-leaved trees (m3ha−1) 0.35 0.021

Grasses cover (%) 0.61 <0.001

Field layer cover (%) 0.65 <0.001

Number of species 0.57 <0.001

Dwarf shrubs cover (%) 0.58 <0.001

Herbs cover (%) 0.43 <0.001

Ground layer cover (%) 0.73 <0.001

Distance from the forest edge (m) 0.34 0.029

Distance from the path (m) 0.36 0.011

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idaea, V. myrtillus, Calluna vulgaris, Melampyrum pratense, P. schreberi, Hylocomiumsplendens and Dicranum polysetum did not occur frequently on the paths (Fig. 1b).

Discussion

Our results showed that trampling is important in changing the forest understoreyvegetation in sub-xeric urban forests studied. The effects of the forest edge were not asclear, but did penetrate tens of metres into the forests. In mesic urban forests of the samearea the effects of forest edges were as important as the effects of trampling in shapingforest understorey vegetation (Hamberg et al. 2008). Microclimatic edge effects may be

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Fig. 3 Three-dimensional GNMDS ordination (log-transformed) of sample plots away from the paths atnorthern, eastern, southern and western sub-xeric forest edges (n=82). Dimensions 1 and 2 are according to(a) distance from the forest edge (centroids ± SD of the sample plots for different distances from the edge areshown in the insert) and (b) edge aspect (centroids ± SD of the sample plots 0–18 m from the forest edges areshown in the insert). The length of each vector indicates the correlation between the vector and theunderstorey vegetation (see Table 4). See Fig. 1 for variable explanations. c Species ordination of the samesample plots. Species occurring in at least four sample plots are presented. Species abbreviations arepresented in Appendix A

592 Urban Ecosyst (2010) 13:583–603

more pronounced in thicker and more nutrient rich forests, such as mesic sites, than in sub-xeric ones, which are naturally quite open receiving e.g. higher solar radiation. Thus, theeffects of human disturbances in terms of edge effects and trampling appear not to havesimilar effects on different plant communities in urban areas.

Effects of the edge

Vegetation communities of sub-xeric forests were changed at eastern, southern and westernedges suggesting that the edge effect may penetrate up to 50 m into the forest interiors, whereasat northern edges the effects of the edge may be very weak or absent. Similar edge penetrationdistances were observed at mesic urban forest edges facing south to west (Hamberg et al. 2008).Other vegetation studies have shown that edge effects may penetrate deeper at south-facingedges (20–60 m) than at north-facing edges (0–30 m) (Fraver 1994; Honnay et al. 2002; Palikand Murphy 1990; Wales 1972), except in a study by Hylander (2005) who concluded thatedge effects penetrated similar distances at north-facing as at other forest edges.

Table 5 Generalized linear mixed model results for the plant species and species groups occurring in at least30% of the vegetation sample plots in sub-xeric urban forests (see Table 2). Sample plots next to and awayfrom the paths are included in the models (i.e., on-path plots were excluded). Coefficients and p-values of thepath variables are presented except for the occurrence models of Dicranum polysetum and Vaccinium vitis-idaea. These species occurred in almost every plot and differences from the path edge into the untrampledvegetation and between wear classes were not detected. One-tailed p-values are given for the variables,because we had predictions for plant species responses to trampling (obtained from the literature) before theanalyses were performed. Statistically significant p-values are indicated in boldface

Model pathdist a wearclass Lb wearclass Q wearclass C

Coeff. p Coeff. p Coeff. p Coeff. p

Vacciniummyrtillus

cover 0.093 0.150 −0.146 0.307 −0.261 0.167 −0.087 0.358

occur. 0.090 0.291 −0.983 0.025 −0.075 0.444 −0.163 0.363

Pleuroziumschreberi

cover 0.034 0.337 −0.594 0.016 −0.302 0.119 0.063 0.388

occur. 0.002 0.496 −0.099 0.440 −1.083 0.068 −2.290 0.002

Dicranumpolysetum

cover 0.082 0.107 0.149 0.236 0.160 0.214 −0.054 0.390

occur. – – – – – – – –

Dicranumscoparium

cover −0.366 0.002 0.693 0.009 0.953 0.003 −0.627 0.017

occur. −0.086 0.301 1.418 0.004 −0.119 0.409 −0.623 0.079

Vacciniumvitis-idaea

cover 0.180 0.001 0.056 0.366 0.208 0.106 0.388 0.008

occur. – – – – – – – –

Melampyrumspecies

cover −0.057 0.303 −1.087 0.003 −0.081 0.415 −0.528 0.032

occur. 0.035 0.413 −0.768 0.059 0.454 0.180 −1.153 0.005

Grasses cover 0.071 0.288 0.640 0.044 −0.474 0.084 0.458 0.077

occur. −0.232 0.117 −0.596 0.149 −0.284 0.319 0.233 0.311

Tolerantspecies

cover 0.129 0.199 −0.646 0.138 −1.045 0.016 −0.370 0.149

occur. 0.021 0.452 0.041 0.467 −0.360 0.226 −1.089 0.007

Edgefavouringspecies

cover −0.352 0.005 −0.656 0.102 1.361 0.015 0.256 0.357

occur. −0.037 0.417 0.516 0.133 1.025 0.019 −0.145 0.383

a pathdist = distance from the path edge (m)b wearclass L = linear response, wearclass Q = squared response and wearclass C = cubic response fortrampling intensity classes 1–4

Urban Ecosyst (2010) 13:583–603 593

Reasons for differences between northern and other edges may relate to microclimatechanges between edge aspects. In the daytime solar radiation is lowest at north-facing edgesin the northern hemisphere (Chen et al. 1993). Other microclimatic effects associated withsolar radiation, such as vapour pressure deficit, temperature and litter moisture, may beweaker at north-facing edges compared to edges facing to the east, west and south (Matlack1993), resulting in cooler and moister north-facing edges (Honnay et al. 2002; Huggard andVyse 2002). However, microclimatic factors were not measured in this study, and thenumber of vegetation sample plots at north-facing edges was low.

Plant species composition at edges may be affected by edge aspect (Palik andMurphy 1990;Ranney et al. 1981). Kivistö and Kuusinen (2000) showed that epiphytic lichen speciesdiversity was lower at sunny south-facing edges than in forest interiors, but no difference indiversity was detected between the edge and the interior of north-facing edges. Furthermore,weedy species richness may be higher at south to west-facing edges, as these edges provide

VACCINIUM MYRTILLUS

0 1 2 3 4

0

10

20

30

40

50

0

0.25

0.5

0.75

1

PLEUROZIUM SCHREBERI

0 1 2 3 4

0

5

10

15

20

25

30

0

0.25

0.5

0.75

1

DICRANUM POLYSETUM

0 1 2 3 4

0

5

10

15

20

25

30

0

0.25

0.5

0.75

1

DICRANUM SCOPARIUM

0 1 2 3 4

0

0.5

1

1.5

2

2.5

3

0

0.25

0.5

0.75

1

CO

VE

R P

ER

CE

NT

AG

E (

%)

VACCINIUM VITIS-IDAEA

0 1 2 3 4

0

5

10

15

20

25

30

0

0.25

0.5

0.75

1

SP

EC

IES

OC

CU

RR

EN

CE

0 1 2 3 4

0

0.5

1

1.5

2

2.5

3

0

0.25

0.5

0.75

1

0 1 2 3 4

0

0.5

1

1.5

2

2.5

3

0

0.25

0.5

0.75

1

MELAMPYRUM SPECIES

0 1 2 3 4

0

1

2

3

4

5

0

0.25

0.5

0.75

1

0 1 2 3 4

0

5

10

15

20

0

0.25

0.5

0.75

1

DISTANCE FROM THE PATH EDGE (m)

GRASS SPECIES TOLERANT SPECIES EDGE FAVOURING SPECIES

Fig. 4 Species and species group responses to trampling. Upper parts of the figures show cover responses andlower parts the species probabilities of occurrences in wear class 1 (—), wear class 2 (- - -), wear class 3 (∙∙∙) andwearclass 4 (∙−∙). Responses next to and away from paths were drawn using predicted values of the GLMMs at easternedges, and values on the paths (left of 0 m from the path edge) are means in each wear class (see Tables 2 and 5)

594 Urban Ecosyst (2010) 13:583–603

an adequate amount of light for weeds to invade the forests (Brothers and Spingarn 1992;Fraver 1994; Honnay et al. 2002). Although the edge effect changed plant species covers andprobabilities of occurrences at sub-xeric urban forest edges, we did not find any invasion ofspecies not belonging to sub-xeric sites. Results from more nutrient rich, mesic urban forestsin the same area revealed that an increase in soil fertility at south to west-facing edgesincreased the number of species benefiting from higher soil fertility (Hamberg et al. 2008;Malmivaara-Lämsä et al. 2008b). However, poorer sub-xeric soils may prevent urbaninvaders from establishing at these forest edges (see also Honnay et al. 2002). Yet, the numberof species was higher at sub-xeric forest edges than interiors indicating that species poor sub-xeric vegetation may change towards more species rich plant communities near edges.

At sub-xeric urban forest edges the covers of sensitive moss species decreased and thecovers of grass and herb species increased. These findings are supported by earlier resultsfrom urban mesic forest edges (Hamberg et al. 2008). Also at pine dominated forest edgesin Sweden, mosses, but also dwarf shrubs (Vacciniun vitis-idaea and V. myrtillus) werelower in cover near the edge line than further from the edge (Jakobsson and Nilsson 2005).Light-demanding broad-leaved trees were abundant both at sub-xeric and mesic type urbanforest edges (see Hamberg et al. 2008). An increase in the number of broad-leaved treesmay have considerable effects on the abundances of understorey species, such asdiminishing the cover of mosses and favouring herb species at edges (cf. Saetre et al.1997). A high number of broad-leaved trees may be the reason for low covers of Dicranumpolysetum and high covers of V. vitis-idaea at eastern edges (see Table 1, Appendix B,Fig. 2). In addition, high covers of dwarf shrubs at edges (see Fig. 3a-b) may be explainedby the high cover of V. vitis-idaea there, because another abundant dwarf shrub V. myrtilluswas low in cover near the edge line (see Fig. 2). However, tree variables, i.e. the totalvolume of trees and the proportion of conifers vs. broad-leaved trees in this study did notexplain the high cover of grasses at eastern edges (see Appendix B, Fig. 2).

This study indicated that at least a 50 m edge zone is needed at edges facing east, south andwest to preserve sub-xeric vegetation communities in urban areas. This is well in agreementwith earlier mesic type results (Hamberg et al. 2008). Assuming a 50 m edge area at all edgeaspects, a circular forested area 1 ha in size includes 1%, a 2 ha patch 14%, a 3 ha patch 24%,a 5 ha patch 36%, a 10 ha patch 52% and a 50 ha patch 77% core area where understoreyvegetation is preserved unchanged. Narrow forests may be totally affected by the edge, andtherefore the shape of a forest patch should be taken into consideration when estimating theamount of unaffected interior habitat (Bannerman 1998; Ewers and Didham 2006). Thereforewe suggest that forest patches should be compact and at least 3 ha in size in urban areas inorder to preserve natural sub-xeric and mesic forest vegetation (see also Matlack 1994).

Effects of trampling

The sub-xeric urban forest vegetation was altered by trampling on the paths, but tramplingalso had an effect on vegetation off the paths. The cover of Vaccinium vitis-idaea increasedwith increasing distance from the path edge. A decrease in the cover and occurrence ofnatural forest vegetation on paths and an increase in cover and occurrence with increasingdistance from the path edge seems to be common phenomena (Godefroid and Koedam2004; Hamberg et al. 2008; Roovers et al. 2004). In sub-xeric forests studied here and inmesic forests studied earlier in the greater Helsinki area (Hamberg et al. 2008) the effects ofpaths extended 4–8 m from the path edge and corresponded with results from earlier studiesin which the spatial extent of the path effect was 3–10 m (Benninger-Truax et al. 1992;Godefroid and Koedam 2004; Roovers et al. 2004).

Urban Ecosyst (2010) 13:583–603 595

Trampling intensity on the paths also affected the covers and the probabilities of occurrencesof species off the paths. Forest species, such as Vaccinium myrtillus, Pleurozium schreberi andMelampyrum species, decreased in cover or probability of occurrence with an increasingamount of trampling. On the other hand, more tolerant species, low in cover in untrampledvegetation, such as Dicranum scoparium and grasses, increased in cover or probability ofoccurrence as trampling increased. Observed changes in the seemingly untrampled vegetationnear paths may be due to occasional trampling next to the paths or due to changes inmicroclimatic or soil conditions, e.g. increase in temperature, drought, pH and nutrientconcentrations on paths and at path edges after long lasting trampling (Liddle 1997;Malmivaara-Lämsä et al. 2008b). However, clear increases in the number of ruderal ordisturbance-loving species, or those benefiting from increased nitrogen or base saturation on,or just next to paths were not observed in sub-xeric vegetation, unlike in mesic urban forestsand in some earlier studies (Benninger-Truax et al. 1992; Godefroid and Koedam 2004;Hamberg et al. 2008; Roovers et al. 2004). Yet, an increase in grass cover with increasingtrampling intensity of the path may be explained by an increase in soil fertility on and next tothe paths (see e.g. Angold 1997). In the Rocky Mountain National Park, USA, trailside plantcommunities were affected by path use so that some species were restricted along lightly,some along moderately and some along heavily trampled paths (Benninger-Truax et al.1992). In that study, forest species richness was greater along lightly and moderately thanalong heavily trampled paths, similar to results from urban sub-xeric forests.

At urban sub-xeric forest edges the effects of trampling were more pronounced in relation toedge effects, in contrast to mesic forest edges in the same area (Hamberg et al. 2008). An earlierstudy concluded that urban sub-xeric forest vegetation is more sensitive to trampling thanurban mesic forest vegetation (Malmivaara-Lämsä et al. 2008a). Sub-xeric forests are usuallymore open than mesic forests, and therefore recreational use may be more intensive than inmesic forests. In sub-xeric forest vegetation studied here the most abundant and typicalbryophyte species, such as P. schreberi, Hylocomium splendens and Dicranum polysetum,were sensitive to trampling. Special attention should be paid to the ground layer vegetation(e.g. mosses) in cities, since the covers of these species in the greater Helsinki area, forexample, are less than half of that of rural areas (Malmivaara-Lämsä et al. 2008a). However,two of the most successful species benefiting from trampling in sub-xeric forests studied weremosses, e.g. Pohlia nutans and D. scoparium, which can grow as very low forms on severelytrampled paths (see also Hamberg et al. 2008; Koponen 1994; Malmivaara et al. 2002). Thetrampling tolerant moss species D. scoparium can also disperse as fragmented pieces(Koponen 1994), which may be a reason for frequent observations of this species on paths.

Implications for management

Although changes in plant species composition between edges and forests interiors in urbansub-xeric forests were not as clear as expected, eastern, southern and western edges showedeffects of the edge penetrating up to 50 m into the forest interior. At northern edges theeffects of the edge may be minimal or absent, but more research is needed to verify this. Werecommend an edge buffer zone of 50 m around the core area of urban forest patches,where natural forest understorey vegetation can exist. Therefore, remnant urban forestsshould be at least 3 ha in size, and as compact as possible.

Trampling is an important factor shaping understorey vegetation in urban forests. The sub-xeric forest vegetation investigated here is sensitive to trampling. Although visible effects oftrampling on paths or other worn out areas are easily observed, we showed that trampling can

596 Urban Ecosyst (2010) 13:583–603

have an effect on the seemingly untrampled vegetation at least 4 m from the path edge,changing plant species covers and occurrences off the paths. It is important to guide people’smovement in order to prevent the creation of an extensive spontaneous path network wherevegetation between paths may be totally affected by trampling effects shown in this study.

Acknowledgements We thank Hannu Rita for his help in planning the sampling design, MinnaMalminvaara-Lämsä for assisting in the field, Bob O’Hara for statistical advice and Sisko Salminen forher help in modifying the figures. The cities of Helsinki, Vantaa and Espoo, and The Finnish Forest ResearchInstitute allowed us to work in their forests. The study was partly funded by the University of Helsinki, thecity of Helsinki, the Maj and Tor Nessling Foundation, The Metsämiesten Säätiö Foundation and HelsinkiUniversity Centre for Environment (HENVI).

Appendix A

Average covers and occurrences (=occ, i.e. the percentages of sample plots in which theplant species were found) of vascular plants, bryophytes and lichens at northern, eastern,southern and western sub-xeric urban forest edges. Values at northern edges representdistances up to 18 m from the forest edge

NORTH EAST SOUTH WEST

n=30 n=74 n=79 n=73

cover % occ cover % occ cover % occ cover % occ

Vascular plants Abbreviation eda tr

Acer platanoides Acer plat I I 0.01 7 0.00 0 0.00 0 0.00 0

Agrostis capillaris Agro capi T T 0.27 3 0.00 0 <0.01 1 0.00 0

Anemone nemorosa Anem nemo T I 0.00 0 0.07 3 0.00 0 0.00 0

Arctostaphylos uva-ursi Arct uvau T I 0.60 3 0.00 0 0.00 0 4.03 12

Betula spp. Betu spp I I 0.07 7 <0.01 1 0.00 0 0.04 4

Calamagrostisarundinacea

Cala arun T I 0.00 0 0.84 12 0.06 4 0.05 1

Calamagrostis epigejos Cala epig T I 0.17 3 0.00 0 0.05 3 0.34 5

Calamagrostis spp. Cala spp 0.00 0 0.01 1 0.00 0 0.00 0

Calluna vulgaris Call vulg T I 1.81 17 1.31 23 4.28 19 2.61 19

Carex spp. Care spp. 0.00 0 0.02 4 0.00 0 0.03 3

Convallaria majalis Conv maja T T 0.00 0 0.93 5 0.46 8 0.53 10

Deschampsia flexuosa Desc flex T I 0.03 3 9.61 57 0.87 11 0.85 18

Epilobium angustifolium Epil angu T I 0.13 7 0.00 0 0.00 0 0.00 0

Festuca ovina Fest ovin T T 1.43 3 0.03 1 0.43 4 0.00 0

Goodyera repens Good repe S S 0.02 3 0.00 0 0.00 0 0.00 0

Hieracium vulgata coll. Hier vulg 0.20 3 0.00 0 0.00 0 0.00 0

Linnea borealis Linn bore S S 0.00 0 0.01 1 0.57 6 0.04 7

Luzula pilosa Luzu pilo T I 0.21 20 0.38 19 0.15 6 0.41 8

Lycopodium spp. Lyco spp. 0.00 0 <0.01 1 0.00 0 0.00 0

Maianthemum bifolium Maia bifo S I 0.00 0 0.25 9 0.04 4 0.07 4

Melampyrum pratense Mela prat T I 3.87 43 1.00 18 2.16 37 0.89 23

Melampyrum sylvaticum Mela sylv T I 0.17 3 0.23 7 0.44 5 0.86 5

Melampyrum spp. Mela spp. T I 2.83 20 <0.01 1 0.04 3 0.02 3

Urban Ecosyst (2010) 13:583–603 597

NORTH EAST SOUTH WEST

n=30 n=74 n=79 n=73

cover % occ cover % occ cover % occ cover % occ

Picea abies Pice abie I S 0.00 0 0.00 0 0.18 3 0.00 0

Pinus sylvestris Pinu sylv T S 0.07 13 0.02 12 0.12 24 0.03 16

Poa spp. Poa spp. T T 0.01 7 <0.01 1 0.15 8 0.03 1

Populus tremula Popu trem T I 0.00 0 0.04 1 0.18 5 0.00 0

Pteridium aquilinum Pter aqui T I 0.00 0 0.00 0 0.47 3 0.41 3

Rumex spp. Rume spp. T T 0.00 0 0.00 0 0.00 0 0.02 3

Seedlings Seedl. 0.02 17 0.01 4 0.01 6 <0.01 1

Solidago virgaurea Soli virg T S 0.00 0 0.04 3 0.00 0 0.00 0

Sorbus aucuparia Sorb aucu I I 0.30 40 0.25 31 0.08 14 0.06 16

Trientalis europaea Trie euro S I 0.17 3 0.02 4 0.22 9 0.27 11

Vaccinium myrtillus Vacc myrt S S 25.62 73 20.59 66 18.42 56 14.87 48

Vaccinium vitis-idaea Vacc viti S S 7.07 63 15.11 87 12.27 82 15.25 92

Viola spp. Viola spp. 0.00 0 0.03 1 0.00 0 0.00 0

Bryophytes and lichens

Aulacomnium palustre Aula palu I I 0.00 0 0.24 9 0.00 0 0.00 0

Brachythecium spp. Brac spp. T S 1.16 20 1.60 28 0.39 11 0.27 10

Ceratodon purpureus Cera purp T T 0.00 0 0.00 0 0.66 3 0.00 0

Certraria islandica Cetr isla T T 0.05 13 0.12 3 0.03 3 0.01 5

Cladina rangiferina Cladina rang T S 0.00 0 0.00 0 0.00 0 0.04 4

Cladina spp. Cladina spp. 0.00 0 0.00 0 0.03 3 0.00 0

Cladonia spp. Clad spp. I S 0.05 7 0.09 14 0.08 11 0.09 21

Dicranella spp. Dicra spp. 0.00 0 0.00 0 0.00 0 0.03 1

Dicranum majus Dicr maju S S 0.00 0 <0.01 1 0.00 0 0.00 0

Dicranum polysetum Dicr poly S S 12.17 83 10.93 80 12.91 76 23.40 95

Dicranum scoparium Dicr scop S I 1.14 13 0.51 41 0.73 43 1.38 38

Dicranum spurium Dicr spur 0.00 0 0.00 0 0.03 1 0.00 0

Hepaticae Hepa 0.00 0 0.06 7 0.02 3 0.01 1

Hylocomium splendens Hylo sple S S 2.77 23 2.07 22 0.71 14 1.89 16

Plagiothecium spp. Plag spp. I 0.00 0 <0.01 4 <0.01 1 0.01 1

Pleurozium schreberi Pleu schr S S 21.02 93 13.25 84 11.52 65 11.91 88

Pohlia nutans Pohl nuta T T 0.27 17 0.27 14 0.15 15 0.12 21

Polytrichum commune Poly comm T I 0.00 0 0.16 5 0.00 0 0.84 5

Polytrichumjuniperinum

Poly juni T T <0.01 3 <0.01 3 0.01 1 0.00 0

Ptilidium ciliare Ptil cili 0.00 0 0.06 3 0.00 0 0.05 4

Ptilium crista-castrensis Ptil cris S S 0.00 0 0.00 0 0.03 1 0.00 0

Rhytidiadelphussquarrosus

Rhyt squa T T 0.00 0 0.43 5 0.00 0 0.00 0

Sanionia uncinata Sani unci 0.34 13 <0.01 1 0.00 0 0.00 0

Sphagnum spp. Spha spp. 0.00 0 0.07 4 1.16 3 0.32 4

a Predicted responses to the edge (ed); T = edge favouring, I = indifferent to the edge, S = edge sensitive.Trampling responses (tr.); T = moderate to high trampling tolerance, I = low trampling tolerance, S = verylow trampling tolerance

598 Urban Ecosyst (2010) 13:583–603

Model

Intercepta

tree

volumeb

conifer%

cpathdistd

wearclass

Le

wearclass

Q

Coeff.

pCoeff.

pCoeff.

pCoeff.

pCoeff.

pCoeff.

p

Vaccinium

myrtillus

cover

−1.148

0.046

−0.002

0.043

−0.003

0.447

0.422

<0.00

1−0

.295

0.137

−0.261

0.14

6

occur.

0.64

70.527

−0.004

0.017

0.003

0.760

0.250

0.02

3−1

.573

<0.001

−0.460

0.13

9

Pleurozium

schreberi

cover

−2.182

<0.001

−0.001

0.353

<0.001

0.952

0.330

<0.00

1−0

.731

0.003

−0.251

0.15

3

occur.

2.80

80.081

−0.005

0.052

0.005

0.710

0.967

<0.00

1−1

.483

0.015

0.175

0.39

2

Dicranu

mpo

lysetum

cover

−3.658

<0.001

−0.001

0.441

0.016

0.009

0.315

<0.00

1−0

.203

0.148

0.274

0.07

9

occur.

1.47

10.170

<0.001

0.981

0.016

0.138

1.816

<0.00

1−1

.790

<0.001

−1.321

0.00

5

Dicranu

mscop

arium

cover

−6.833

<0.001

0.002

0.107

0.001

0.824

−0.350

0.00

50.218

0.251

0.111

0.36

4

occur.

−0.436

0.534

0.001

0.697

0.001

0.843

−0.322

0.00

40.628

0.038

−0.595

0.03

9

Vaccinium

vitis-idaea

cover

−1.655

<0.001

<−0

.001

0.845

−0.007

0.014

0.383

<0.00

1−0

.181

0.131

0.142

0.19

6

occur.

1.63

50.588

0.002

0.717

0.001

0.972

2.187

0.05

2−1

.533

0.154

0.031

0.49

1

Melam

pyrum

species

cover

−4.077

<0.001

−0.002

0.111

−0.005

0.381

0.270

0.00

1−1

.227

0.001

−0.139

0.34

6

occur.

−0.674

0.451

0.002

0.381

−0.009

0.289

0.242

0.02

4−1

.455

<0.001

0.424

0.15

9

Grasses

cover

−1.911

<0.001

−0.002

0.204

−0.005

0.300

0.246

0.00

50.146

0.321

−0.435

0.07

3

occur.

1.22

90.229

−0.001

0.664

−0.010

0.217

0.092

0.24

9−1

.330

0.004

−0.648

0.09

1

Tolerant

species

cover

−5.989

<0.001

−0.001

0.562

<−0

.001

0.964

0.159

0.07

7−0

.631

0.110

−1.054

0.00

7

occur.

−0.411

0.704

<0.001

0.880

0.006

0.484

−0.236

0.03

50.271

0.241

−0.222

0.27

8

Edg

efavo

uring

cover

−4.891

<0.001

0.001

0.738

−0.016

0.038

−0.250

0.00

9−0

.849

0.039

1.144

0.03

0

species

occur.

0.596

0.430

−0.002

0.243

−0.016

0.019

−0.084

0.24

50.320

0.182

0.620

0.04

4

Appendix

B

Generalized

linearm

ixed

modelresults

forthe

plantspecies

orspeciesgroups

investigated

(see

Table2).S

ampleplotson,nexttoandaw

ayfrom

thepaths

areincluded

inthemodels.Coefficientsandp-values

ofthevariablesinvestigated

arepresented.

One-tailedp-values

aregivenforvariables,because

predictio

nsfrom

theliteraturewereobtained

forplantspecies

responsesto

tram

plingandedge

effectsbefore

theanalyses

wereperformed.H

owever,for

tree

volume(m

3ha

−1)andconiferpercentage

(%)two-tailedp-values

aregiven.

Statistically

significantp-values

areindicatedin

boldface

Urban Ecosyst (2010) 13:583–603 599

Mod

elwearclass

Caspect

Sf

aspect

Wg

edgelin

hedgesq

edgecub

Coeff.

pCoeff.

pCoeff.

pCoeff.

pCoeff.

pCoeff.

p

Vaccinium

myrtillus

cover

−0.109

0.30

50.34

80.28

00.60

80.16

9−0

.034

0.04

6−0

.001

0.097

<0.001

0.021

occur.

−0.174

0.31

50.67

40.24

31.54

40.05

90.00

10.48

30.00

10.050

––

Pleurozium

schreberi

cover

0.03

20.44

00.55

70.14

7−0

.326

0.25

5−0

.048

0.00

7−0

.001

0.025

<0.001

0.003

occur.

−0.420

0.22

0−1

.787

0.05

3−0

.410

0.40

0−0

.081

0.08

1−0

.002

0.018

<0.001

0.025

Dicranum

polysetum

cover

−0.083

0.33

0−0

.285

0.26

40.29

90.23

40.01

60.15

4<−0

.001

0.244

<0.001

0.405

occur.

0.31

00.26

1−2

.079

0.03

23.06

20.113

0.03

40.19

4−0

.003

0.002

<0.001

0.076

Dicranum

scoparium

cover

−0.656

0.01

41.32

40.116

1.10

10.15

9−0

.116

0.05

0−0

.001

0.275

<0.001

0.149

occur.

−0.272

0.18

90.32

80.24

40.08

70.42

8−0

.038

0.00

5–

––

–

Vaccinium

vitis-idaea

cover

0.34

50.01

5−0

.007

0.48

9−0

.079

0.37

5−0

.004

0.22

8–

––

–

occur.

0.02

70.49

1− 0

.608

0.35

3−0

.134

0.46

80.02

90.30

3–

––

–

Melam

pyrum

species

cover

−0.479

0.03

50.85

70.15

5−0

.783

0.19

60.06

30.02

0<−0

.001

0.417

<−0

.001

0.053

occur.

−0.583

0.05

20.58

40.24

6−0

.083

0.46

10.07

60.01

4−0

.001

0.196

<−0

.001

0.053

Grasses

cover

0.34

80.111

−2.205

0.02

7−1

.384

0.00

7−0

.030

0.08

0<−0

.001

0.266

<−0

.001

0.243

occur.

0.33

10.18

60.08

50.47

0−1

.782

0.04

00.01

90.33

30.00

10.182

<−0

.001

0.059

Tolerantspecies

cover

0.00

50.49

41.07

60.18

60.48

40.35

3−0

.153

0.03

9−0

.001

0.288

<0.001

0.181

occur.

−0.538

0.05

5−1

.139

0.13

7−0

.367

0.36

2−0

.050

0.17

1−0

.007

0.053

<−0

.001

0.084

Edg

efavouringspecies

cover

0.77

40.10

30.38

20.35

2−0

.770

0.26

4−0

.029

0.03

9–

––

–

occur.

0.08

80.40

30.17

10.40

6−0

.010

0.49

4−0

.008

0.27

70.00

10.010

––

Mod

elaspect

S:edgelin

iaspect

W:edgelin

jaspect

S:edgesq

aspect

W:edgesq

aspect

S:edgecub

aspect

W:edgecub

Coeff.

pCoeff.

pCoeff.

pCoeff.

pCoeff.

pCoeff.

p

Vaccinium

myrtillus

cover

0.03

80.06

90.06

10.04

6<−0

.001

0.33

0−0

.002

0.01

4<−0

.001

0.171

<−0

.001

0.093

occur.

0.03

10.06

50.00

60.40

1−0

.001

0.08

6−0

.004

<0.00

1–

––

–

Pleurozium

schreberi

cover

0.03

00.09

70.05

60.01

7−0

.001

0.13

6<0.00

10.23

9<0.00

10.411

<−0

.001

0.039

occur.

0.07

70.13

90.19

80.30

20.00

20.08

00.01

30.31

8<−0

.001

0.141

<0.001

0.359

600 Urban Ecosyst (2010) 13:583–603

Mod

elwearclass

Caspect

Sf

aspect

Wg

edgelin

hedgesq

edgecub

Coeff.

pCoeff.

pCoeff.

pCoeff.

pCoeff.

pCoeff.

p

Dicranum

polysetum

cover

0.01

70.19

60.01

60.22

00.00

10.13

1<0.00

10.31

4<−0

.001

0.046

−0.001

0.409

occur.

−0.003

0.47

1−0

.113

0.15

80.00

30.00

2<0.00

10.49

4<−0

.001

0.034

<0.001

0.290

Dicranum

scoparium

cover

0.06

20.20

50.13

30.03

7<0.00

10.42

70.00

10.09

1<−0

.001

0.385

<−0

.001

0.056

occur.

0.01

60.17

30.03

20.04

1–

––

––

––

–

Vaccinium

vitis-idaea

cover

0.01

00.06

60.01

50.02

6–

––

––

––

–

occur.

−0.020

0.38

2−0

.040

0.29

3–

––

––

––

–

Melam

pyrum

species

cover

−0.081

0.01

4−0

.085

0.02

9<−0

.001

0.24

30.00

10.12

0<0.00

10.063

<0.001

0.115

occur.

−0.087

0.02

0−0

.105

0.01

50.00

10.20

00.00

10.25

2<0.00

10.096

<0.001

0.069

Grasses

cover

−0.058

0.23

3−0

.013

0.37

6−0

.001

0.28

3−0

.001

0.17

2<0.00

10.274

<0.001

0.060

occur.

0.00

30.48

4−0

.091

0.04

8−0

.003

0.03

5−0

.002

0.12

0<0.00

10.433

<0.001

0.012

Tolerantspecies

cover

0.17

60.02

50.05

60.28

40.00

10.25

8<0.00

10.43

7<−0

.001

0.074

<− 0

.001

0.478

occur.

0.07

40.10

90.01

50.40

00.00

70.04

90.00

70.05

7<0.00

10.122

<0.001

0.082

Edg

efavouringspecies

cover

−0.007

0.39

50.01

90.22

0–

––

––

––

–

occur.

−0.027

0.06

2−0

.005

0.39

1<−0

.001

0.26

5−0

.001

0.18

7–

––

–

aIntercept=easternaspect

btree

volume=vo

lumeof

trees(dbh

≥5cm

,m

3ha

−1)on

tree

sampleplot

arou

ndthevegetatio

nsampleplot

cconifer%

=proportio

nof

conifers

around

vegetatio

nsampleplot

(%)

dpathdist=distance

from

thepath

edge

(m)

ewearclass

L=lin

earresponse,wearclass

Q=squaredresponse

andwearclass

C=cubicresponse

fortram

plingintensity

classes1–4

faspect

S=thedifference

betweenthelevelsof

easternandsouthern

aspect

at38

mfrom

theforestedge

(edgelin

=edgesq

=edgecub=0)

gaspect

W=thedifference

betweenthelevelsof

easternandwestern

aspect

at38

mfrom

theforestedge

(edgelin

=edgesq

=edgecub=0)

hedgelin

=distance

from

theforestedge

minus

averagedistance

from

theforestedge

(m),edgesq

=edgelin

2andedgecub=edgelin

3.E

dgelin,edgesqandedgecubdescribe

the

effect

oftheedge

foreasternaspect

iaspect

S:edg

elin,aspect

S:edg

esqandaspect

S:edg

ecub

=thedifference

betweeneasternandsouthern

edge

respon

securves

jaspect

W:edgelin,aspect

W:edgesqandaspect

W:edgecub

=thedifference

betweeneasternandwestern

edge

response

curves

Urban Ecosyst (2010) 13:583–603 601

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